Pneumatic hydraulic travel control apparatus



y 4,1949. 1 "E. A. RO'CKWELL' 2,47 ,954

PNEUMATIC HYDRAULIC TRAVEL CONTROL APPARATUS File d June 4, 1945 64 fQH/AED A-POCKWELL Patented May 24, 1949 UNITED STATES PATENT Fries.

PNEUMATIC HYDRAULIC TRAVEL CONTRQL. APPARATUS Edward A. Rockwell, fllewcland ohio Application June 4, 1943, SeriallNo. 489,711.

17 Claims.

1 Myinvention relates particularly to an apparatus-forcontrolling the-movement of any desired part to bemoved by power in such a wayobtained inthepart to be'moved. Another object isrtoprovide a mechanism of this character in which. the power applied for moving the said part is a pneumatichydraulicmechanism; In.

other words, thesaid mechanism preferably comprises'a hydraulic means for controlling the application of pneumatic. power to the movement ofsaid part. Another object is to provide a mechanism of'the above character for moving. the said part'in opposite directions while maintaining the coordination of the, movement thereof with that offjthe control means. Another object .is to provide means for eliminating chattering and vibra'e ti'on in the manual control mechanism used in connection-therewith. Further objects of my invention will appear from the detailed description of the same hereinafter.

Whilemy-invention is capable of being carried out in many different Ways for the purpose of. illustrationl have shown only one form of my apparatus in the accompanying drawings inwhich thefigure is a diagrammatic representation of an airi hydraulic travel controlling. apparatus applied fongcontrolling the operation of a locomotivereversegear.

Inthe drawings I have shown a hand .lever I carried .on apivot pinZto which it is fastened by, a.. split. ring, 3. havingkatightening screw 4. Withinthehand lever I thereis a helical spring, ii'ina longitudinal recess 6; the upper end of whichspring rests against a plunger pawl I which slidesin therecess 6'but has a laterally directed tooth 8. projecting from a slot 9 in the side of tlie'lever- I'; A'rod II! is fastened to the upper end of'the pawl T which is attached at its upper end to. a manually operable plunger I I extending out through the top of the hand lever I. The laterally directed" tooth 8 of thepawl I engages with an internal rack I2 'ona segmental bracket: I3 which is:fast'ened'on a lever housing I4 which carries tliegpivot-pin 2; 'Ihe-handlever I has a downwardly directed arm I5 carrying aroller I6,

2 within theleverhousing I4, whichbears against; the lower side of; a plug" I! in a hollow plunger 18 whichisreciprocable-within a cylindrical extension I9 on the lever housing I4; The hollow plunger I8-' has'an internalannular shoulder 26:

to receive on-its underface a head'Z-I- of a subsidiaryplunger 22 having around the same a spring; 23 resting at its lower end against the shoulder ZIJtand its upper end against the under face of a master cylinder piston 24 formed on the. subsidiaryplunger. 22. The said plunger 'fl has arrinternal cylindrical chamber 25which're ceives a valve. rod 25 having a head 2T1ocated below an internal annular. flange 28 on thepistorr:

I 24; Around the rod 26 and above the piston-.21-

there is provided a spring 29, the upper-end of which is received beneath an apertured'partition 3B withinthe'cylindrical extension I9. Thespring? 29' normallyforces'the piston 24 downwardly and thespring 23"'SerVes' toprevent the transmissionof vibrationsfrom the controlling mechanism back to the hand lever I; The said partition 30" has an opening 31 through which the valve rod 26* passes and openings 32 for the passage of hy= draulicliquid in the apparatus, and. which liquid maybe-of any desired character. on its upperendthe'valve rodgZfihas a cylindrical valve mem- 1 ber-33 beneath whichthere is located a coil spring 34'seating on the top of the partition 30. Furthermore, the said cylindrical valve member 33"" hasthereon a conical liquid compensating valve 35 which seats against a valve seat 36in the-top) of the cylindrical extension I9 so'as'to control the passageof'hydraulic liquid through a passage-:

way 3'! connected by a pipe 38 to the bottom of ahydraulic liquid reservoir 39 having lateral flanges 40 and holes ll to support the reservoir" The said reservoir is 42 having the usual in any desired manner. equipped with a filling cap :vent aperture 43.

of which from time to'time the accumulated-air can be discharged. Within the travel control, cylinder" 41 there is" a plunger 53, one end of which is connected to a piston -54 in a control cylinder 55 having a casing 56 which also forms a part of the casing for the cylinder 41 and on which the eye member 58 is located. At the two ends of the cylinder 55 there are provided air bleeder screws and 58 similar to the air bleeder screw 50. Furthermore, the said piston 54 has attached thereto a plunger rod 53 having a pivotal connection fill to a link El which in turn has a pivotal connection E2 to a bell crank lilting lever 63 carried on a lifting shaft 64!- pivoted in a fixed bracket 65. The lifting bell crank lever -33 has an arm 66 for pivotal attachment to a lifting link 61 for lifting a radius rod 67a, the upper and lower positions of which, respectively, determine the forward or rearward drive or the locomotive, with any usual known form of locomotive reverse gear valve mechanism, such for example as those disclosed on pages 975 to 977 of Marks Mechanical Engineers Handbook, first edition, 1916, published by McGraw-Hill Book Company, Inc, New York. The piston 54 is adapted to be moved by power, by means of the supply and withdrawal of the hydraulic liquid under pressure through a pipe 68 entering the cylinder 55 at one side of the piston 54 and a pipe 69 entering the said cylinder at the other side of said piston. The pressure liquid supplied and withdrawn from the pipe E3 is obtained from the reservoir 39 by means of a pipe 70 supplying the liquid to a valve chamber H for liquid compensation, and which has a lateral port 12 connected to the pipe 68. The valve chamber H is located in a power unit l3 provided for moving the piston 54 towards the right. Likewise, the liquid received and discharged from the pipe 69 is obtained in a similar manner from a branch pipe 14 connected to the pipe ill which in turn is connected to a liquid compensation valve chamber in a power unit it, for moving the piston 14 towards the left. The valve chamber 15 has a port 17 which connects it to the pipe 69;

The liquid supplied under manual pressure through the pipe controls the operation of both the power units 13 and 16 by means of a branch pipe 18 connected to the said pipe 45. The pipe 78, accordingly, is connected to a plunger chamber 19 in the power unit 73 and which has a plunger 80 contacting with a valve plunger 8| to which there is attached a dished outlet valve 82 operating in a chamber 83 having air vents 84. The outlet valve 82 is adapted to seat on a diaphragm 35, of rubber or rubberlike material, the periphery of which is located in a fixed position in the power unit '73. The inner portion of the diaphragm 935 is carried by a valve sleeve member 86 which has a central longitudinal passageway 8? provided with a shoulder 88 supporting a helical spring 89, the upper end of which rests against a partition 90 in said unit 13 having air apertures 9|. The sleeve member 86 is, furthermore, supported within a supporting diaphragm 92 of rubberized fabric, the periphery of which is fastened to the power unit 13. Furthermore, a plurality of inclined passageways 93 connect the chamber ill with an annular chamber 94 located beneath a dished inlet valve 95 formed on the periphery of the valve member 86. Above the inlet valve 95 and between the two diaphragms 85 and 92 there is an air inlet chamber 96 which is connected to a compressed air supply pipe 97 leading to an air inlet chamber 98 in the power unit it which in turn is connected to a compressed air inlet pipe 99 supplied with air under any desired pressure, for example 100 to 150 lbs. per square inch. In

the power unit 13, furthermore, there is a main piston H29 operated by the compressed air when admitted through the apertures 9| and provided with a central stop llli which engages with the partition in the retracted position of the main piston lfill. A coil spring I02 is supported at its lower end by the main piston l 00 and at its upper end by the power unit 13 within a chamber i051, and within said chamber I03 there is, furthermore, provided a hollow pressure increasing plunger I04 having a central longitudinal chamber Ill-5 to receive a valve rod I06 which passes through a hole [ill in the power increasing plunger Hit, and which is provided with a head 88 within the chamber 95. A plurality of apertures Hi9 connect the chamber lllli with a pressure-increasing chamber lllila. A chamber Ill] is connected by apertures ill with the valve chamber 7!, said apertures Ill being located in a partition l I2 supporting a spring I It at one end while the other end of said spring rests against a cylindrical valve member ll l having a conical valve ll5 cooperating with a valve seat H6 in said power unit 19.

The said liquid under manual pressure received from the pipe l8 into the plunger chamber 19 is also conveyed by a pipe I I! to a plunger chamber H3 in the power unit 16 and having an air bleeder screw H9 like the air bleeder screws above referred to. In this instance the manual pressure liquid is received above a valve operating plunger l20, which is located above a coil spring |2l carried in an extension l22 of the said unit 76. It will be noted that while the plunger ill in the power unit 73 is normally down so as to open the valve 82 and close the valve 95, the plunger valve operating plunger I2!) is normally in the up position, due to the spring lZl, until it is moved downwardly by the manual pressure liquid received through the pipe Hi. This valve operating plunger i261 operates against a valve plunger I23 constructed the same as the valve plunger 8| in the power unit it, the said plunger I23 serving to operate an outlet valve i2 3 and an inlet valve l25 constructed the same as the corresponding valves 82 and in the power unit 73. In fact, the other parts of the power unit l6 are constructed in the same manner as de scribed in detail in connection with the power unit 13.

In the operation of the apparatus, when the hand lever l is moved into forward position, as shown in the drawing, the locomotive reverse gear is operated thereby so as to drive the locomotive forwardly, and when the hand lever l is moved downwardly to its lowermost position the said gear is operated to drive the locomotive rearwardly. Likewise, when the hand lever l is in its middle position on the segment It the said gear is in a position in which the locomotive is brought to rest. These positions of the hand operated lever for controlling the locomotive reverse gear are the usual positions provided for the manual operation of the locomotive reverse gear from the cab of a locomotive. Thus, for example, when the hand operated lever l is moved towards the forward position, as shown in the drawing, by the release and reengagement of the pawl 8 with the rack l2, it will be noted that the compressed air from the pipe 99 is being admitted to the interior of the power unit 16 and released from the power unit '13, thereby moving the main piston of said power unit 16 upwardly and the main piston in the power unit 13 downwardly and accordingly supplying the pressure liquid under intensified pressura through the pipe' se to thee right. side: of the piston 54 and withdrawing; the pressure liquid: the? pine. 6.8: from the;- left. side thereof.

Int any given position; of the piston. 54; a co ordinate position. is present; in the'hand lever l due to. the: travel control plunger: 53? which is connected by the pipes 46: and QEwWiththevplunger I 8: connected tothe hand lever: l1 Furthermore,

in: the downward position of either; of. the mainpistons-in the power units 13 and 1 6, respectively, itwill: be noted?- that. the" respective liquid; com

pensating valves 35.=and H5 are open for'readejustmentlof the liquid receivediirom thexreservoir 39 However; it will; be: noted that. these: liquid compensation valves are notopen: atv the same time; Aocordinglyeachpf said valves willcompensate for-the expansion and; contraction, as

wellasdealsage; in itszparticular hydraulic passagesindependently of; the, other. When the hand=lever [is-movedtowards the centrallposition: on. the segment l3.- the: piston.- 54- will; he shiftedztowards its centralpositionin the chamber. 55 by. the application of modulated amounts of; the. pressureliquid received: in; the left. end

of the cylinder 56-iromthe-pipe-68t connected to thes;power-.unit-13, andbythe modulating release of; corresponding amounts of thepressureliquid fromtherightendof the; chamber 55 throughthe :pipe. (i9: These; operations are accomplished bv'first the-.closing-; of; the. valve 82, and when:

closed the subsequent opening of the valve 95 and}. simultaneously a similar. operation; in the reverse order, of thevalves I24 and l25- in the power unit-l6. However, due-tothe plunger 89 being; moved.- forwardly: hydraulically and. the plunger. IZMoeing-moved forwardly by the spring I2 lthe valvesconnected thereto are capable of independent movement, and especially as said. valves are-subject to different pneumatictpressures, respectively, in the two=cylinders I93 and asthe two intensifying cylinders Ila/shave different' liquid: compensations. When. the parts are-at :rest-in any. such intermediate position. of

the piston 54 the pneumatic valves of: the two power units 13-and16 willloe in closed position;

When the piston 54 ismovedlto theright endof the-cylinder.- 5&-by; the movement of the hand lever l. to. its lowermostr position on the segment l3 the locomotive is being .-driven in the rearward direction. In the left end. position of thewpiston 541it. will be understoodthat" the: compensating valve-35rwill be :in opentposition.

Thus; .thelocomotivereverse gear-will be shifted" in, either direction-by theapplicatiom of power applied in modulatedamountsain either direction.- of. movement thereof, andwith the desired amount of power being applied thereto to-relievethe manual force required in operating the shifting mechanism accordingly. This mode of operation ofvthelocomotive reverse gearwill, furthermore; eliminate the hysteresis and hunting inthe same' due to the fact .thatthepi-ston 5M s-held in any givenlposition by thehigh pressure liquid operating. against the opposite sides of the said piston. However, to eliminate the-transmission of.allappreciable-vibratory efiects from the re.- verse. -gearltothe-handlever l the. spring ra hes been; introduced; whichiscarried; on the subsidiary; piston member 22:ha-vinga lost motionconnection with the manual. operating plunger |8-.. The spring 23*isprovided, also, .for the purpose oi-yicldingin case of the'backingupof the liquid,-. to; avoid, breakages-. In thissway; themanual lever I 1 will her-smooth inwoperation and? cam bee shited with little orno; efforts to: bring:

about the:changeszin:positionsonthe:reverse gear:-

byegradual transition from: one:;p.ositiom to'zan other andswithouta the tramsmissionofiany: vibraetions; chattering: or: hysteresis from: the: reverse;- ear.mechanism'ztoztheamanuallyoperatedjever l2 While- IQhave: described-my?invention alcovexindetail; I wish it' to: be I understood: that many; changes may: be madesthereinwvithouti departing:

from the spirit of: the-same:

luclaim:

1. In combination; a-partiadaptedw-to .bemoved;

a, cylinder :having: a hydraulically operated-piston connectedthereto and:hy.draulic: means for rap.- plying liquid. under-'pressurer'to opposite sides of the hydraulic pistonnhaving, a liquid pressure-producin'g means connected'to' one. s-idevofthe. piston andi aaseparate liquid pressure producing means connected: to the: other side of. the piston: so as;

to-apply the pressure liquid to. one: s-ideathereof and.coordinatelysrelease.pressureliquidfrom-theother sides'thereof including compressed-rainpowerr units, having cylinders and-compressed air pistons fitting therein; said compressed airpistonshavingr connected thereto liquid pressure: producing: plungersaswel-l ashydrau'lic compensation valvesx provided with a commonzsource of supply, andhy draulic: controlling meanszoperable at will,=.hav-

ill'gJfi; hydraulic. connection and valve mechanism connected thereto, for controlling the-operation;

of the compressed air pistons-ofisaidspowersunits:

to apply pressure simultaneously-to: the liquid;

OI-libOthSldBS of theshydraulic: piston or tor-apply: pressure to one side of the hydraulic piston while releasingliquid from the other side to cause moves ment ofithe hydraulic piston, said hydraulic-conetrol-ling means having a hydraulic compens ation valve. leading. to said source:

2; In combination, apart adapted: to: bemoved; a cylinder having a hydraulically operated piston -con-n'ectedthereto, and hydraulicmeans-ior; ap-

plying. liquid under pressure. to opposite sides;

of the hydraulic piston having a liquid pressure producingmeans connected to. one side. of the piston and a separate liquid" pressure producing. meanssconnected to the other side. of the piston. so'asto apply the pressure. liquid to one side. thereof and: coordinately. release pressure-liquid from the other sidethereoiincluding. compressed.

ainpower units, having cylinders. and compressed air pistons. fitting therein, said compressedair pistons having; connected thereto liquid. pressure producing plungers as well as hydraulic.compen sation valves provided'with a common source of supply, hydraulic controlling means operable at" "will; having a hydraulic connection and .valve mechanism connected. thereto, for controlling the" operation of the ccmpressedair'pistons-of said" power units to apply pressure simultaneously tflthellqllld on-b'oth sides of the'hydraulic' piston or to apply pressureto one side of the" hydraulic piston While releasing-liquid 'f'rom the other side" to cause movement of the'hydraulic" piston; said hydraulic controlling means" having a hydraulic compensation valve leading to said. source, and a hydraulic travel coordinating-plum ger operable with said'hydraulic' piston having a hydraulic connection with the-hydrauliccontrolling means.

3. In combination, a-partad'aptedto be' moved, a cylinder having a hydraulically operated-piston connectedthereto, hydraulic-means; compris ingra: plurality of-"power units, for applyingaliquid under. pressureto opposite sides of thehydraulic piston sosasr to apply the pressureliquid tosone side thereof and; coordinately: release pressurea liquid from the other side thereof, each of said power units having inlet and outlet air valves as well as an air piston and a power intensifying hydraulic plunger each of said power units having as well a liquid compensation valve operatively attached to the air piston, and a single hydraulic means, having a liquid compensation valve in hydraulic communication with said other plurality of liquid compensation valves, for simultaneously controlling the position of inlet and outlet air valves of said power units.

4. In combination, a part adapted to be moved, a cylinder having a hydraulically operated piston connected thereto, and hydraulic means for applying liquid under pressure to opposite sides of the hydraulic piston having a liquid pressure producing means connected to one side of the piston and a separate liquid pressure producing means connected to the other side of the piston so as to apply the pressure liquid to one side thereof and coordinately release pressure liquid from the other side thereof, including compressed air power units, having cylinders and compressed air pistons fitting therein, said compressed air pistons having connected thereto liquid pressure producing plungers as well as hydraulic compensation valves provided with a common source of supply and hydraulic controlling means operable at will, having a hydraulic connection for controlling the operation of the compressed air pistons of said power units to apply pressure simultaneously to the liquid on both sides of the hydraulic piston or to apply pressure to one side of the hydraulic piston while releasing liquid from the other side to cause movement of the hydraulic piston, said hydraulic controlling means having a hydraulic compensation valve leading to said source, each of said units having inlet and outlet air valves operatively connected to the hydraulic connection as well as a power intensifying hydraulic plunger attached to the compressed. air piston.

5. In combination, a part adapted to be moved, a cylinder having a hydraulically operated piston connected thereto, and hydraulic means for applying liquid under pressure to opposite sides of the hydraulic piston having a liquid pressure producing means connected to one side of the piston and a separate liquid pressure producing means connected to the other side of the piston so as to apply the pressure liquid to one side thereof and coordinately release pressure liquid from the other side thereof, including compressed air power units, having cylinders and compressed air pistons fitting therein, said compressed air pistons having connected thereto liquid pressure producing plungers as well as hydraulic compensation valves provided with a common source of supply, hydraulic controlling means operable at will, having a hydraulic connection, for controlling the operation of the compressed air pistons of said power units to apply pressure simultaneouly to the liquid on both sides of the hydraulic piston or to apply pressure to one side of the hydraulic piston while releasing liquid from the other side to cause movement of the hydraulic piston, said hydraulic controlling means having a hydraulic compensation valve leading to said source, and a hydraulic travel coordinating plunger operable with said hydraulic piston having a hydraulic connection with the hydraulic controlling means, each of said power units having inlet and outlet air valves operatively connected to the hydraulic connection as well as a power intensifying hydraulic plunger attached to the air piston.

6. In combination, a part adapted to be moved, a cylinder having a hydraulically operated piston connected thereto, and hydraulic means for applying liquid under pressure to opposite sides of the hydraulic piston having a liquid pressure producing means connected to one side of the piston and a separate liquid pressure producing means connected to the other side of the piston so as to apply the pressure liquid to one side thereof and coordinately release pressure liquid from the other side thereof, including compressed air power units, having cylinders and compressed air pistons fitting therein, said compressed air pistons having connected thereto liquid pressure producing plungers and hydraulic controlling means operable at will, having a hydraulic connection, for controlling the operation of the compressed air pistons of said power units to apply pressure simultaneously to the liquid on both sides of the hydraulic piston or to apply pressure to one side of the hydraulic piston while releasing liquid from the other side to cause movement of the hydraulic piston, each of said power units having air inlet and outlet valves operatively connected to the hydraulic connection and one of said power units having a hydraulic plunger for closing the outlet valve and the other power unit having a springpressed hydraulically releasable plunger normally closing the outlet valve.

'7. In combination, a part adapted to be moved, a cylinder having a hydraulically operated piston connected thereto, and hydraulic means for applying liquid under pressure to opposite sides of the hydraulic piston having a liquid pressure producing means connected to one side of the piston and a separate liquid pressure producing means connected to the other side of the piston so as to apply the pressure liquid to one side thereof and coordinately release pressure liquid from the other side thereof, including compressed air power units, having cylinders and compressed air pistons fitting therein, said compressed air pistons having connected thereto liquid pressure producing plungers, hydraulic controlling means operable at will, having a hydraulic connection, for controlling the operation of the compressed air pistons of said power units to apply pressure simultaneously to the liquid on both sides of the hydraulic piston or to apply pressure to one side of the hydraulic piston while releasing liquid from the other side to cause movement of the hydraulic piston, and a hydraulic travel coordinating plunger operable with said hydraulic piston having a hydraulic connection with the hydraulic controlling means, each of said power units having air inlet and outlet valves operatively connected to the hydraulic connection and one of said power units having a hydraulic plunger for closing the outlet valve and the other power unit. having a spring-pressed hydraulically releasabl plunger normally closing the outlet valve.

8. In combination, a part adapted to be moved, a cylinder having a hydraulically operated piston connected thereto, and hydraulic means for applying liquid under pressure to opposite sides of the hydraulic piston having a liquid pressure producing means connected to one side of the piston and a separate liquid pressure producing means connected to the other side of the piston so as to apply the pressure liquid to one side thereof and coordinately release pressure liquid from the other side thereof, including compressed air power units, having cylinders and compressed air pistons aavogese fitting therein; said com-pressed air pistons havconnected i thereto iiq-uid pressure producing "plungers as well as hydraulic compensation valves provided'with a commonsource'of supply and hydrauliccontroliingmeans'op erable atwill, hav- "ing' a hydraulic-connection for controlling the operation of the compressed air pistons of said power unit to apply pressure simultaneously'to the liquid on both sides of thehydraulio piston "or to apply pressure to one side of the hydraulic piston whil releasing liquid from the other side to *cause movementof thehydraulic piston, said hydraulic controlling means having a hydraulic 'compensationyalve' leading to said source, each "of said "power units having inlet and outleta-ir valves operativelyconnected to the hydraulic connectionas well as-a'power intensifying plunger attached to the compressed air *piston,*the power intensifying plungers having liquid compensating valves adapted to open inthe retracted positions of theair pistons.

-9. In combination-a part adapted to be moved, a-cylinder having a hydraulically operated piston connected thereto, and hydraulic meansfor applying *liquid under-pressure to opposite sides of the hydraulic piston having a liquid pressure producing means connected to one side of the piston i-arid .;a separatezliquidspressure.producing means connected to the other side of theipistonsoaas :to apply the pressure liquid to one side thereof and coordinately release pressure liquid from the other side thereof, including compressed airpower :units, having cylinders and-compressed air-pistons lfitting therein,saidcompressedeair' pistons having connected thereto liquid pressure producing plungers aswellas hydraulic compensation valves provided with acommon source of supply and hydraulic controlling means operable at will; having.v a hydraulic connection for controlling the operation of the compressedwair pistonsof-said 1 pow er units to apply pressure simultaneously. to theliquid on both sides-of-=the hydraulic piston or-toapply pressure to oneside -of the hydraulic piston while releasing-liquid from= the other-side to cause movementof "the hydraulic piston,--said hydraulio means having-a hydraulic compensation valve leading tosaidrsource; and a hydraulic travel coordinating plunger operable with said hydraulic piston having-ahydraulic connection with =the'hydraulic-controlling---means, *each of said power unitshaving-inletand-outlet air-valves operatively connectedto the hydraulic connection as well as -a power intensifying plunger attached to the compressed air piston, the power intensifying plungers having liquid compensating valves adapted to open in the retracted positions of the air pistons.

10. In combination, a part adapted to be moved, a cylinder having a hydraulic piston connected thereto, and hydraulic means for applying liquid under pressure to opposite sides of the hydraulic piston so as to apply the pressure liquid to one side thereof and coordinately release pressure liquid from the other side thereof, including compressed air power units, having movable walls responsive to movement by the compressed air, adapted to simultaneously apply the pressure from compressed air to the pressure liquid on both sides of the hydraulic piston and hydraulic controlling means, including a valve mechanism for admitting compressed air to said units, operable at will for controlling the operation of said power units, said controlling means having a manual lever provided with a rack and pawl and with a master cylinder provided with a piston and hav- 10 ing aplunger operable bythe manual 'lever-and a spring interposed between the master-cylinder piston and the plunger.

11. Incombination, a part adapted to be moved, a cylinder having a hydraulic piston connected thereto, and hydraulic means for applying liquid under pressure to oppositesides oitl-"ie-'-liydraulic piston so as to apply the pressure liquid to one *side thereof and coordinately release pressure liquid from the other side-thereof, including compressed air power-units, having movable walls responsive to movement-by the compressed air, adapted to simultaneously apply the pressure i rcm coinpressedair to thepressure liquid on both sides of the hydraulic piston, hydraulic econtrolling means, including a valve mechanism for admitting compressed air tosa-id units, operable at-will for controlling the operation of said power units, and a hydraulic travel coordinating plunger operable with said piston having a hydraulic con- "nection with the hydraulic controlling means, said controlling means havinga manual lever pro- :vided' with a rack and pawl and with a-master cylinder provided with a piston'andhaving'a plunger operable by thernanual lever and'a spring interposed between the master cylinder piston and the plunger.

"l2. In combination, apart to bemoved; means ior applying a varying degree of hydraulic-pressure, a source of air pressure controlledthereby, fluid pressure operated-hydraulic pressure "ideveloping apparatus, including two movable walls anda pairof movable liquid compensating valves responsive to said air pressure aswellas a valve mechanism having two valves controlling the access of the air pressur to saidwalls re-spectively, and independentlyoperable valve actuating plungers operated by said hydraulic pressure, said valves being constructed to receive the-air'pressureand apply to saldpait, by the-action of one of said plungers against a previous bias ;of one ofsaid valves, a hydraulic pressure whi'ch'decreases coordinately as the first mentioned hydraulic 1 pressure increases.

13. In combination, a part to bemoved; means for-applyinga varying degree of-hydraulic pres- {sure,-a source of air pressure controlled'ther'eby, fluid pressure operated hydraulic'pressurc ideveloping apparatus, including two movable' walls and apair of movable liquid compensating valves responsive to said air pressure as wellas'a valve mechanism having two valves controlling the access-of the air pressure to saidwalls, respectively, and independently operable valve actuating plungers operated by said hydraulic pressure, said valves being constructed to receive the air pressure and apply to said part, by the action of one of said plungers against a previous bias of one of said valves, a hydraulic pressure which decreases coordinately as the first mentioned hydraulic pressure increases, so as to move said part in one direction, and by the action of another one of said plungers a hydraulic pressure for moving said part hydraulically in the opposite direction, one of said two valves being connected to said source of air pressur for supplying a hydraulic pressure which increases as said first mentioned hydraulic pressure increases.

14. In combination, a part to be moved, means for applying a varying degree of hydraulic pressure, a source of air pressure controlled thereby, fluid pressure operated hydraulic pressure developing apparatus, including two movable walls and a pair of movable liquid compensating valves responsive to said air pressure as well as a valve mechanism having two valves controlling the access of the air pressure to said walls respectively, and independently operable valve actuating plungers operated by said hydraulic pressure, having on each movable wall a pressure increasing piston connected thereto, as well as a cylinder for the piston, said valves being constructed to receive the air pressure and apply to said part, by the action of one of said plungers against a previous bias of one of said valves, a hydraulic pressure which decreases coordinately as the first mentioned hydraulic pressure increases.

15. In combination, a part to be moved, means for applying a varying degree of hydraulic pressure, a source of air pressure controlled thereby, fluid pressure operated hydraulic pressure developing apparatus, including two movable walls and a pair of movable liquid compensating valves responsive to said air pressure as well as a valve mechanism having two valves controlling the access of the air pressure to said walls respectively, and independently operable valve actuating plungers operated by said hydraulic pressure, having on each movable wall a pressure increasing piston connected thereto, as well as a cylinder for the piston, said valves being constructed to receive the air pressure and apply to said part, by the action of the said plungers against a previous bias of one of said valves, a hydraulic pressure which decreases coordinately as the first mentioned hydraulic pressure increases, so as to move said part in one direction, and by th action of another one of said plungers a hydraulic pressure for moving said part hydraulically in the opposite direction, comprising a valve device having a pressure increasing piston connected thereto, as well as a cylinder for the piston, one of said two valves being connected to said source of air pressure for supplying a hydraulic pressure which increases as said first mentioned hydraulic pressure increases.

16. In combination, a part to be moved, means for applying a, varying degree of hydraulic pressure, a source of air pressure controlled thereby, fluid pressure operated apparatus including a valve mechanism, said apparatus having a plunger and pressure increasing piston connected thereto, as well as cylinders for the plunger and piston, constructed to receive the air pressure andapply a hydraulic pressure so as to move said part in one direction, and a fluid pressure operated device, including a valve mechanism, having a plunger and pressure increasing piston connected thereto, as well as cylinders for the plunger and piston, constructed to receive the air pressure and deliver a hydraulic pressure so as to mov said part in the opposite direction, the valve mechanism of said apparatus and the valve mechanism of said device being connected together hydraulically for respective hydraulic self-adjustment independently of each other.

17. In combination, a part to be moved, means for applying a varying degree of hydraulic pressure, a source of fluid pressure difiering from the atmospheric pressure, controlled thereby, fluid pressure operated apparatus, including a valve mechanism, constructed to receive the said fluid pressure and apply a hydraulic pressure so as to move said part in one direction, and a fluid pressure operated device, including a valve mechanism, constructed to receive the said fluid pressure and deliver a hydraulic pressure so as to move said part in the opposite direction, the valve mechanism of said apparatus and the valve mechanism of said device being connected together hydraulically for respective hydraulic self -adjustment independently of each other.

EDWARD A. ROCKWELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 486,095 Elmes Nov. 15, 1892 561,272 Ongley June 2, 1896 752,491 Warren Feb. 16, 1904 813,209 Holmes Feb. 20, 1906 897,907 Lang Sept. 8, 1908' 962,257 Rockwell June 21, 1910 1,570,097 Sumner Jan. 19, 1926 1,938,311 Avery Dec. 5, 1933 1,946,715 Shield Feb. 13, 1934 2,239,893 J ackman Apr. 29, 1941 2,252,482 Gates Aug. 12, 1941 2,316,320 Dewandre Apr. 13, 1943 2,352,344 Rockwell June 27, 1944 2,352,357 Almond June 27, 1944 FOREIGN PATENTS Number Country Date 194,995 Germany Feb. 4, 1908 685,217 France Mar. 31, 1930 769,257 France June 5, 1934 798,816 France Mar. 11, 1936 

